Method of forming brake drums



July 6.1937 .1. E. BATIE 2,086,488

METHOD OF FORMING BRAKE DRUMS Filed Dec. 11, 1935 2 Sheets-Sheet 1 E EJ 1:1.

wasepzzzzl BY W mow ATTO RN EYIS {July 6, 1937. J. E. BATIE METHOD OF FORMING BRAKE DRUMS 2 Sheets-Sheet 2 Filed Dec. 11, 1933 INVEI ITOR Josey/ell ZBatze BY )V W ATTORNEYS Ftenteci July 6, 1937 NITED STATES PATENT OFFICE METHOD OF FORMING BRAKE DRUMS Joseph E. Batie, Detroit, Mich, assignor to Kelsey-Hayes Wheel Company,-Detroit, Mich., a corporation of Delaware Application December 11, 1933, Serial No. 701,932

Claims.

5 and which also has various other advantageous 1 features.

Brake drums are most generally formed from pressed sheet steel having a relatively low carbon content and asa consequence the braking surface of the drum is relatively soft and is easily scored. Certain other constructions have been devised to overcome this defect but these have greatly complicated the process of manufacture and have not proven altogether satisfactory. It is therefore the primary object of the present invention to obtain a construction which can be easily manufactured and which provides a braking surface of sufficient hardness to be satisfactory in its performance. To accomplish this, I first form the blanks from sheet steel of such composition that with proper heat treatment there will be developed in the metal a lamular. perlitic structure. However such material can not be completely fashioned to the desired form by cold pressing, nor can it be successfully hot pressed by methods which have heretofore been employed in brake drum manufacture. This is for the reason that where the heated blank is brought in contact with the extended surface of a die, it is very quickly reduced in temperature to a point unsuitable for further fashioning.

T overcome the defects just described, I have devised aprocess for fashioning the heated blank with a minimum loss of heat through contact with the fashioning tools and for obtaining a productwhich is true in form and which has the desired physical characteristics. My invention therefore consists in the novel process and product as hereinafter set forth.

In the drawings:

Figs. 1 to 10 inclusive are diagrams illustrating the successive steps of the process in forming my'improved drum; I

Fig. 11 is a vertical section through the truing and sizing die;

Fig. 12 is a vertical central section of the spinning apparatus.

As above stated, the material employed for forming jzny improved drum is a sheet steel of a composition which under suitable heat treatment will develop a lamular perlitic structure. Various specific compositions may be used for this purpose, but as one example I may use a steel containing Carbon .65 to .75 Manganese .65 to .85 Silicon .15 to .30

A circular blank A of this material is first fashioned to form a bowl B, having a diameter considerably larger than the diameter of the finished drum. This operation may if desired be performed by cold pressing, providing that the blank is first annealed to suitably soften the same. As 10 shown in Fig. 1, the blank A is pressed into the die C by the plunger die D. On the other hand,if desired, it may behot fashioned without annealmg.

After the bowling operation, the blank is pierced to form a central round aperture D of proper size. It is then heated to a temperature of from 1600 to 1700 F., after which it is engaged with a spinning machine on which the subsequent fashioning operations are performed. This spinning machine preferably comprises a revolvable arbor E having mounted thereon a head F corresponding to the particular brake drum to be fashioned and having a cylindrical portion F which is slightly less in diameter than the brake drum to be spun thereabout. The lower surface F of this head is also of a contour corresponding to that desired for the web of the drum. G is a plunger beneath the arbor E and carrying on its upper end a clamping head G suitably fashioned on its upper surface. A pilot pin H of a diameter 30 to fit withinthe aperture D is located in a central recess in the head G and insertable in a recess H in the head F. The plunger G is forced up ward preferably by hydraulic means (not shown) so as to clamp the web portion of the bowl between the heads G and F and to also suitably fashion the clamped portion of said web.

When the heated bowl blank is thus engaged with the spinning machine, rotary motion is imparted to the arbor E after which the following operations are performed' 'First, a roughing roll I preferably having its axis extending radially from the axis of the drum, is raised and contacts with the portion of the bowl which projects outward from the clamped portion. This will contract the diameter of the bowl and change its shape to a substantially cylindrical form, as indicated at J, leaving an obliquely extending flange J at its upper end. Following the operation of the roll I, a roll K is raised to contact with the web portion of the blank which projects beyond the clamped portion thereof conforming such projecting portion to the contour of the lower face of the head F, as shown in Fig. 5. The next operation, Fig. 6, is performed by a roll L which is moved in radially to further reduce the diameter of the cylindrical portion J of the drum, but which still leaves this portion slightly spaced from the cylindrical portion F of the head F. Where it is desired "to provide the drum with a ribbed outer surface, this is formed by a roll M, Fig. ,8, having peripheral ribs thereon, said roll being moved radially inward and pressed into the cylindrical portion J. During this operation the portion of the drum in contact with the roll M is momentarily forced against the surface F of the head F so as to furnish the required opposing pressure for fashioning the ribs. This contact is, however,

only momentary and of a limited area so that the loss of heat from the blank to the head F is relatively small. Furthermore, this operation Slightly enlarges thediameter of the cylindrical portion J so that after the completion of theoperation the drum is spaced from the head F on all sides. Thus with all of the spinning operations the contacts between the heated blank and the spinning tools are of very limited area so that the blank retains the proper temperature until after the completion of these operations.

Brake drums are generally provided with aradially outwardly extending flange for reinforcing the end of the cylindrical portion which is opposite that merging into the web. This flange J may be formed by the same roll L whichfashions the cylindrical portion J. If, however, the axis of the roll L is parallel to the axis of the drum and said roll is forced radially inward, there is danger that the flange J will be drawn so as to thin the metal in the portion which connects it to the cylindricalportion J. This is avoided, as shown in Figs. 6 and 9, by leaving the flange J'to extend obliquely during the operation of the roll L, and after removal of the blank from the spinning machine, flattening down this flange in dies as indicated in Fig. 9. Another method of accomdrum parallel to the axis thereof. The roll is moved inward in a direction perpendicular to its axis, thereby pressing radially inward against the cylindrical portion J of the drum and upward against'the flange J The result will be the simultaneous reducing of the diameter of the drum and the forming of the flange in a plane perpendicular to the axis and without any drawing or stretching'of the metal. I, After removal of the formed drum from the spinning machine, it is subjectedto a heat treatment which will impart to the metal the desired physical structure. This with the specific composition given above consists in heating the drum, to a temperature above the critical point, such as 1450 F. and then gradually cooling at a predetermined rate to a temperature of 1100 F. It is then quenched in a caustic solution or other suitable-means for removing the scale. Finally, the drum is trued and sized by placing the same in an external sizing die N and inserting an expanding. die 0 which enlargesand trues the cylindrical portion J, as shown in Figs. 10 and 11. In thus expanding the drum there might be danger of overstressing the metal which joins the cylindrical. portion to the web portion. This is avoided by forming during the spinning operation a curved or bulging portion P intermediate the fashioned web. and the cylindrical portion J. Thus during the expanding operation the bulging portion P will be flattened out and will furnish the necessary metal for enlarging the diameter of the cylindrical portion J without over-stressingany portion thereof.

As a modification of the process above described,'the entire fashioningof the drum may be accomplished on the spinning machine.

, as shown in Fig. 2, the heated fiat disk blank A Thus is clamped between the heads F and G of the spinning machine. The bowling is accomplished by a roll Q having a curved tapering or conical form and moving said roll radially inward to round upward the peripheral portion of the blank and to form the bowl. The following operations 1. The method of forming brake drums of high carbon steel which comprises bowling a flat metal blank, heatingthe bowl, clamping the bowlby the web portion thereof and with its outer portion free from contacts, and hot rolling said free portion to refashion the same. i

2. The method of forming brake drums of high carbon steel which. comprises bowling a flat metal blank, piercing a central aperture in the web of. theqbowl concentric with the periphery thereof, heating the bowl, clamping the portion of the web of said heated bowl which surrounds said central aperture, leaving the outer portions of the bowl freefrom contacts and in rolling said hot free portion torefashion the same.--

3. The method of forming brake drums of high carbon steel which comprises bowling a. flatmetal blank, piercing the web portion of said blank to form an aperture therein concentric with the axis of the bowl, heating the bowl, clamping the portion of the web ofthe bowl surrounding said aperture to hold the heatedouter portion thereof free from contacts, spinning the clamped bowl concentric to the axis thereof and moving a roll in contact with the free portion of the spinning bowl to refashion the same. a

a. The method of forming brake drums of high carbon steel which comprises clamping a hot blank by thecentral portion thereof, leaving the outer portions free from contacts, spinning the clampedblankand moving a-roll against the free portion of said blank to refashion the same.

5. The method of forming brake drums of high carbon steel which comprises clamping the central portion of a hot blank to a head havingthe general contour of the drum to be formed,

spinning said head and clamped blank concentric" to the axis of the head, and moving one or more rolls against the free portion of the spinning blank to conform the same to the shape of carbon steel which comprises clamping the cen:

tral portion of a hot blank to a head having the general contour of the drum to be formed, spinning said head'and clamped blank concentric to the axis of the head, moving one or more rolls,

against the free portion of the spinning blank to conform the same to the shape of the head but with the peripheral portion spaced from the periphery of the head to be out of heat conducting contact therewith, and in moving a ribbed roll having its axis parallel to the axis of the blank radially inward against the peripheral portion thereof to progressively press the same momentarily against the periphery of the head, and to fashion external ribs thereon, the portions with the periphery of said blank out of contact with said ribbed roll, being still spaced from the peripheral portion of the head.

7. The method of forming brake drums of high carbon steel which comprises bowling a flat blank, hot rolling the bowl to refashion the same to the desired shape of drum, heat treating the drum to develop therein the desired microstructure and in finally expanding the drum to true and size the same.

8. The method of forming brake drums of high carbon steel which comprises bowling a flat blank, hot rolling the bowl to refashion the same to the desired shape of drum, heat treating the drum to develop therein the desired microstructure, removing the scale and in finally expanding the drum to true and size the same.

9. The method of forming brake drums of high carbon steel which comprises clamping the central portion of a heated blank to a head having the general contour of the interior of the desired drum, spinning said head and clamped blank concentric with the axis of the head, moving a roll having its axis radial with respect to said head against a portion of said blank to conform the same to the end of said head, moving a roll against the portion of said blank extending beyond the periphery of said head to refashion the same into general conformity to the periphery of said head, moving a roll having its axis parallel to the axis of said head radially'inward against the peripheral portion of said blank to more closely conformithe same to the shape of said head but with a slight space between the same and the periphery of the head whereby said peripheral portion is out of heat conducting contact with said head.

10. The method of forming brake drums of high carbon steel which comprises clamping the tion of saidblank to conform the same to the end I of said head, moving a roll against the portion of said blank extending beyond the periphery of said head to refashion the same into general conformity to the periphery of said head, moving a roll radially inward against the peripheral portion of said blank to more closely conform the same to the shape of said head but with a slight space between the same and the periphery of the head whereby said peripheral portion is out of heat conducting contact with said head, and moving a circumferentially ribbed roll having its axis parallel to the axis of said head radially inward to progressively and momentarily press the peripheral portion of said blank against the periphery of said head and to thereby form exterior ribs, the portions of the blank out of contact with the roll remaining still spaced from the periphery of the head to be out of heat conducting relation thereto.

ll. The method of forming brake drums of high carbon steel which comprises bowling a flat metal blank, hot rolling the bowl to refashion the same to the desired form of drum but of a slightly lesser radius and with an annular corrugation adjacent to the juncture between the web and cylindrical portions, heat treating the drum to impart the desired microstructure to the metal thereof and in expanding the drum to true and size the same, said annular corrugation relieving the metal from overstress in said expanding operation.

12. The method of forming brake drums of high carbon steel which comprises bowling a flat blank, hot rolling the bowl to refashion the same to the desired shape of drum, heat treating the drum to develop therein the desired microstructure andcircumierentially pressing the cylindrical portion of the drum to true and size the same.

13. The method of forming brake drums of high carbon steel which comprises fashioning a blank into drum form having integral web and cylindrical flange portions, and hotrolling said cylindrical portion of the drum to extrude therefrom a solid rib on the exterior thereof.

14. The method of forming brake drums of high carbon steel which comprises hot fashioning a blank into drum form having integral web and cylindrical flange portions, and rolling said cylindrical portion while under its original heat to extrude therefrom a solid rib on the exterior thereof.

15. The method of forming brake drums of high carbon steel which comprises bowling a fiat metal blank, hot rolling the bowl to refashion the same to drum form and hot rolling the cylindrical portion of the drum to externally extrude therefrom a solid rib.

I JOSEPH E. BATIE. 

